Introduction: Undisplaced femoral neck fractures (UFNF) are generally treated with in situ internal fixation, and few studies have addressed the impact of closed reduction. The aim of this study was to investigate the clinical outcome of UFNF treated with internal fixation using the Hansson pinloc system after closed reduction.
Patients and methods: This was a retrospective study of 40 patients who underwent internal fixation using the Hansson pinloc system after closed reduction between September 2014 and May 2016. In the present study, posterior tilt, presence of complete fracture, interval from injury to surgery, and changes in activities of daily living were statistically analyzed to investigate the association between nonunion and late segmental collapse (LSC).
Results: Five cases each of nonunion and LSC were identified. The frequency of LSC was significantly higher in patients with preoperative posterior tilt ≥ 20° (p < 0.05). The risks of nonunion and LSC were lower in patients with incomplete fracture (p < 0.05) and fixation within 48 h (p < 0.05). Of the 40 patients, 34 were categorized in the sufficient reduction group fixed with posterior tilt ≤ 5°. Secondary operation rate was lower in the sufficient reduction group (5/34 cases) than in the insufficient reduction group (3/6 cases).
Discussion: The fixation timing < 48 h decrease the risk of fracture healing complications and sufficient reduction may reduce the risk of secondary operation. Preoperative posterior tilt ≥ 20° and complete fractures on CT scans were related to poor prognosis.
Keywords: Closed reduction; Hansson pinloc system; Late segmental collapse; Nonunion; Posterior tilt; Undisplaced femoral neck fractures.